Hearing loss is determined by measuring hearing thresholds, the loudness at which a sound is just barely heard. The louder these sounds must be made to be heard, the greater the threshold and thus the degree of hearing loss. These thresholds are displayed on a graph called an audiogram. The audiogram has two major parts including frequency and intensity.
Intensity (also called loudness): Along the side of the graph, from top to bottom, are the numbers -10 to 120. These numbers represent the amount of energy in the sound. The lower numbers at the top represents the softest sounds and the loudest sound are at the bottom of the audiogram represented by the higher numbers. These numbers are followed by the letters dB, which stands for deciBels.
On the graph, anything above the X or O cannot be heard and anything below can be heard. The < and > or [ and ] marks the softest sounds heard through the bones of the skull which bypass the middle ear and represent hearing at level of the cochlea (inner ear). If the < and > or [ and ] marks are very close to the X’s and O’s the hearing loss is sensorineural and permanent. If they are separated and above the X’s and O’s the hearing loss is conductive or mixed and may be medically treated.
Tympanogram: Measures how well the eardrum moves. This test will tell if there is fluid or negative pressure behind the eardrum or if there is a hole in the eardrum.
Acoustic Reflex: The loudness level that is required before a muscle contraction occurs in the middle ear. It can help identify problems with the ossicles, cochlea, auditory nerve, facial nerve or brainstem.
Otoacoustic Emissions (OAE): Response from the inner ear to a sound. Addresses the function of the cochlea (inner ear) but does not give hearing levels.
Speech Awareness Threshold (SAT): Lowest loudness level that a person can tell that speech is present.
Speech Reception Threshold (SRT): Lowest loudness level that a person can repeat back 2-syllable words.
Word Recognition (WRS): Percentage score of the words understand from a list. Can be done at different loudness levels. This test measures a patient’s word understanding or clarity for speech. It helps the audiologist determine whether hearing aids will help.
Loudness Matching: Measures the loudness (intensity) of a patient’s tinnitus perception.
Pitch Matching: Measures the pitch (or frequency) of a patient’s tinnitus perception.